The present invention is directed to a flame retardant material. More particularly, the present invention pertains to a flame retardant material that uses other than halogenated compounds to enhance the synergistic effects of flame retardancy.
Sheet materials are used in many applications as flame retardants or barriers. Often, in order to meet a specific need or application, these materials are fabricated into sheets or into other shapes to form a part of, or lie adjacent a structure or part of a structure for electrical cabinets containing electrical or electronic devices and the like. These materials can serve not only as a flame retardant, but can also serve as an electrical insulator.
Some known materials use polypropylene (as a homopolymer or as an ethylene polypropylene copolymer) as the “base” material with added flame retardants. Flame retardants include, for example, halogenated organic materials such as, for example, bis(2,3-dibromopropyl ether) of tetrabromobisphenol A, tetrabromobisphenol A-bis(2 hydroxyethyl ether), tetrabromobisphenol A-bis (allyl ether), hexabromocyclodecane, decabromodiphenyl oxide, octabromodiphenyl oxide, penta bromodiphenyl oxide, 2,4,6 tribromophenol, poly-dibromophenylene oxide, bis(tribromophenoxy) ethane, tetrabromophthalic anhydride or tetrabromophthalate diol. The halogenated flame retardant may be combined with a synergist so as to enhance the effectiveness of the halogenated organic flame retardant. The synergist may be a metal oxide such as, for example, antimony oxide or a salt such as, for example, sodium antimonate. The ratio of the halogenated organic flame retardant to the synergist is within the range of from approximately 2:1 to approximately 3:1. One exemplary material is disclosed in U.S. Pat. No. 5,521,003 to Lo et al., which patent is commonly assigned with the present application and is incorporated herein by reference.
While these materials work quite well for their intended purposes, e.g., flame retardancy and electrical insulation, they nevertheless contain halogenated materials and metal oxides, both of which have been found to be materials that should be avoided due to their potentially adverse environmental impact. However, even though these materials have some undesirable constituents, they nevertheless have certain advantageous and beneficial characteristics, such as the ability to be formed (typically by an extrusion process), which allows these materials to be readily shaped or fabricated into rigid flame retardant structures. As a result, other materials are sought that provide like functions and have like “forming” characteristics, but that have less or no severe environmental effects.
Accordingly, there exists a need for a readily extrudable or moldable flame retardant material. Desirably, such a material provides the flame retardancy characteristics of known, presently used materials, while reducing the amount of potentially environmentally hazardous materials. Most desirably, such a flame retardant material eliminates the need for halogenated compounds and metal oxides in the formulation.